The invention relates to the field of medical devices, and more particularly to echogenic catheters, such as needle catheters.
An essential step in treating or diagnosing cardiac tissue or cardiovascular diseases using an interventional catheter is the proper placement of the catheter at a desired location within the patient, which consequently requires accurate imaging of the catheter location within the patient. Although various methods of imaging catheters within a patient are possible, ultrasonic imaging (also referred to as acoustic imaging) would provide several advantages. For example, ultrasonic imaging is very safe for the expected extended time periods required for therapy guidance, unlike CT/EBCT (Electron Beam Computed Tomography) or bi-planar fluoroscopy. Additionally, ultrasound is relatively inexpensive compared to other imaging modalities such as MRI or CT/EBCT, and can provide tissue diagnostics such as wall motion and thickness information.
However, one difficulty is visualization anomalies, including artifacts and overly bright images, in the ultrasonic images of catheters. Such artifacts can provide a misleading and inaccurate impression of the shape and/or location of the catheter within the patient. Additionally, catheter elements can appear so bright and large on the ultrasonic image (called “blooming”) due to their highly reflective nature relative to the anatomy, especially at the gain settings typically used to image the anatomy, that the image of the adjacent anatomy is obscured by the catheter image. For example, metallic portions of catheters can produce strong/high amplitude echoes (bright images), with a pyramid artifact (i.e., a pyramid shape of reverberation (“ringing”) images trailing off in the viewing direction). Similarly, most thermoplastic catheter shafts produce strong/high amplitude direct echoes (bright images). If the gain settings of the ultrasonic imaging system are reduced to improve the image of the catheter (reduce its image and artifact brightness), the image of the anatomy fades significantly to the point of being less visible or not visible at all. Therefore, it would be a significant advance to provide a catheter with improved imaging characteristics by two-dimensional and three-dimensional ultrasonic imaging systems for enhancing the diagnosis and guidance of treatments in the body.